Bottom Line:
There has been much interest in the health effects of dietary fat, but few studies have comprehensively compared the acute metabolic fate of specific fatty acids in vivo.Using the values for isotopic enrichment in the different lipid fractions compared with the test meal, we calculated the contribution of meal fatty acids to the respective fractions.This was significantly greater than for oleate and palmitate (both 3 +/- 0.3%; P < 0.05).

ABSTRACTThere has been much interest in the health effects of dietary fat, but few studies have comprehensively compared the acute metabolic fate of specific fatty acids in vivo. We hypothesized that different classes of fatty acids would be variably partitioned in metabolic pathways and that this would become evident over 24 h. We traced the fate of fatty acids using equal amounts of [U-(13)C]linoleate, [U-(13)C]oleate, and [U-(13)C]palmitate given in a test breakfast meal in 12 healthy subjects. There was a tendency for differences in the concentrations of the tracers in plasma chylomicron-triacylglycerol (TG) (oleate > palmitate > linoleate). This pattern remained in plasma nonesterified fatty acid (NEFA) and very low-density lipoprotein (VLDL)-TG (P Show MeSH

Mentions:
Incorporation of the stable isotope tracers into plasma CE was lower for palmitate and oleate. However, there was marked incorporation of [U-13C]linoleate; the incorporation was over six times greater than the other two fatty acid tracers at 24 h (P = 0.000 for both; Fig. 2A). The increase in [U-13C]linoleate in plasma PL over time was greater and more dynamic compared with [U-13C]palmitate (P = 0.028) and [U-13C]oleate (P = 0.000; Fig. 2B). The concentration of [U-13C]oleate changed little over time, with the concentration only increasing to 0.11 μmol/l by 24 h compared with 0.49 μmol/l for [U-13C]palmitate (P = 0.000) and 0.52 μmol/l for [U-13C]linoleate (P = 0.000). At time 0, the proportion of linoleate, oleate, and palmitate in erythrocyte PL was 7.11 (0.92), 15.1 (0.23), and 38.0 (1.05) mol%, respectively. By 7 h after ingestion of the test meal, fatty acid tracers were detectable in erythrocyte PL. The incorporation of [U-13C]palmitate and [U-13C]linoleate into erythrocyte PL over time was identical such that by 24 h the concentration was 0.16 mg/l for both (Fig. 2C). The concentration of [U-13C]oleate was 75% lower than [U-13C]palmitate (P = 0.000) and [U-13C]linoleate (P = 0.008) by 24 h.

Mentions:
Incorporation of the stable isotope tracers into plasma CE was lower for palmitate and oleate. However, there was marked incorporation of [U-13C]linoleate; the incorporation was over six times greater than the other two fatty acid tracers at 24 h (P = 0.000 for both; Fig. 2A). The increase in [U-13C]linoleate in plasma PL over time was greater and more dynamic compared with [U-13C]palmitate (P = 0.028) and [U-13C]oleate (P = 0.000; Fig. 2B). The concentration of [U-13C]oleate changed little over time, with the concentration only increasing to 0.11 μmol/l by 24 h compared with 0.49 μmol/l for [U-13C]palmitate (P = 0.000) and 0.52 μmol/l for [U-13C]linoleate (P = 0.000). At time 0, the proportion of linoleate, oleate, and palmitate in erythrocyte PL was 7.11 (0.92), 15.1 (0.23), and 38.0 (1.05) mol%, respectively. By 7 h after ingestion of the test meal, fatty acid tracers were detectable in erythrocyte PL. The incorporation of [U-13C]palmitate and [U-13C]linoleate into erythrocyte PL over time was identical such that by 24 h the concentration was 0.16 mg/l for both (Fig. 2C). The concentration of [U-13C]oleate was 75% lower than [U-13C]palmitate (P = 0.000) and [U-13C]linoleate (P = 0.008) by 24 h.

Bottom Line:
There has been much interest in the health effects of dietary fat, but few studies have comprehensively compared the acute metabolic fate of specific fatty acids in vivo.Using the values for isotopic enrichment in the different lipid fractions compared with the test meal, we calculated the contribution of meal fatty acids to the respective fractions.This was significantly greater than for oleate and palmitate (both 3 +/- 0.3%; P < 0.05).

ABSTRACTThere has been much interest in the health effects of dietary fat, but few studies have comprehensively compared the acute metabolic fate of specific fatty acids in vivo. We hypothesized that different classes of fatty acids would be variably partitioned in metabolic pathways and that this would become evident over 24 h. We traced the fate of fatty acids using equal amounts of [U-(13)C]linoleate, [U-(13)C]oleate, and [U-(13)C]palmitate given in a test breakfast meal in 12 healthy subjects. There was a tendency for differences in the concentrations of the tracers in plasma chylomicron-triacylglycerol (TG) (oleate > palmitate > linoleate). This pattern remained in plasma nonesterified fatty acid (NEFA) and very low-density lipoprotein (VLDL)-TG (P Show MeSH